The present invention is in the field of vehicle fuel systems and more specifically it is concerned with a liquid fuel trap (at times referred to also as an expansion tank or an expansion canister).
Vehicle fuel systems comprise, among others, a fuel tank fitted with a filler neck, a variety of fuel valves, a tubing for supplying fuel to the ignition system and a fuel vapor treating system (typically a carbon filter recovery systemxe2x80x94canister) to which fuel vapor from the fuel tank flows and is then used for enriching the fuel mixture fed to the ignition system.
Fuel fluid (in the form, of liquid, droplets, spray and vapor) from the fuel tank flows via the one or more valves which are connected, via suitable tubing, to a liquid trap intermediate the fuel vapor recovery system, and the tank.
The liquid trap receives fuel fluid flowing from the fuel tank which flows at a relatively high velocity owing to pressure and temperature changes, and thus vapor flowing from the fuel tank carries along with it also a considerable amount of fuel liquid in the form of droplets (as a result of venturi effect). The liquid trap entraps the fuel liquid and allows fuel vapor flow towards the vapor recovery system. The fuel liquid then returns back to the fuel tank upon pressure decrease within the fuel tank.
A liquid fuel trap is important in those cases where the various valves fitted within the tank are internally installed, i.e. do not project from an upper wall of the tank, where siphons may be generated at tubes connecting the valves to the liquid trap. Such siphons interfere with venting the tank on the one hand and, on the other hand, interfere with draining the devices.
It is an object of the present invention to provide a liquid trap for a vehicle""s fuel system, which expansion chamber is made of a plastic material and is adapted for fitting within the fuel tank.
The present invention calls for a liquid fuel trap usable in a vehicle""s fuel system, which liquid trap is adapted for fitting within the fuel tank and comprises a relief valve for spontaneously discharging liquid fuel into the fuel tank, when the pressure with fuel tank drops below a predetermined threshold.
According to the present invention there is provided a liquid fuel trap device for a vehicle fuel tank, die device comprising a housing formed with a confined space wide at least one inlet port connectable to a corresponding at least one fuel valve, an outlet port connectable to a fuel vapor recovery system and a fuel liquid discharge valve adapted for discharging liquid fuel from said space into the tank, the housing further comprising a connecting arrangement for attaching the device on an inner surface of an upper wall of the fuel tank.
The liquid fuel trap device is typically made of an essentially impermeable material, though since the device is fitted for mounting within the fuel tank, this feature is not essential.
According to one particular embodiment, the confined space of the housing comprises at least a well portion, said well portion being lowest within the confined space, where the liquid discharge valve is a check valve fitted at a bottom most portion thereof.
The liquid discharge valve, according to one design, is a mushroom-type valve, and by another design is a spring-biased valve, such as, for example, a door-type valve, or a seat-type check valve.
According to an embodiment of the invention, liquid flow from the at least one inlet port is prevented from direct flowing or splashing to the outlet port. By one specific design there is a barrier member between the at least one inlet port and the outlet port. This effect may also be achieved by designing the at least one inlet port and the outlet port at different levels and axially diverted, i.e. not axially extending. Thus, the confined space may be formed with several unleveled chambers, where the inlet and outlet ports are fitted at different levels.
The device, according to one design, is attached to the fuel tank by a securing member formed on the housing and adapted for snap engagement with a connecting member extending from the upper wall of the fuel tank.
The present invention calls also for a fuel system comprising a fuel tank, at least one fuel valve, a fuel recovery system and a liquid fuel trap device located between the at least on fuel valves and the fuel recovery system said liquid trap device comprising a housing formed with a confined space with at lease one inlet port connectable to the corresponding at least one fuel valve, and outlet port connectable to the fuel vapor recovery system, a fuel liquid discharge valve adapted for discharging liquid fuel from said confined space into the tank, and a connecting arrangement for attaching the device on an inner surface of an upper wall of the fuel tank.
According to a specific design, the device is attached to the fuel tank by a connecting member extending from the upper wall of the fuel tank, said connecting member adapted for snap-engagement with a corresponding securing member formed on the housing of the device.